Negative life events may cause chronic pain

Negative life events are a risk factor for the onset of chronic pain, suggesting that psychosocial factors play a role in triggering the development of this condition.

INTRODUCTION
Some people experience chronic, long-term pain with no obvious medical reason. It is thought that this could be caused by stressful events in a person’s life that cause areas of the brain and nervous system to become extra sensitive. Stress is a normal biological response to a threat. The biological stress system is a complicated interaction between the body’s stress hormones, the immune system and the nervous system. Some parts of this are sometimes called the ‘fight or flight’ response.

WHAT DID THE AUTHORS HOPE TO FIND?
The authors hoped to find out more about the causes of chronic pain. They expected to find that chronic pain is caused by a defect in the biological stress system. They also expected to find that the experience of stressful life events could trigger the onset of chronic pain.

WHO WAS STUDIED?
The study looked at 2,039 people who did not have any chronic muscular or joint pain. Everyone in the study was over the age of 18. A questionnaire was then used to identify people who developed chronic pain during the course of the study.

HOW WAS THE STUDY CONDUCTED?
The authors used data from an ongoing study of people with and without depression. They followed these people for 6 years, and looked at whether they developed chronic pain in their arms, legs, back or neck. The authors then worked out whether problems in the biological stress systems or negative or stressful life events were linked to chronic pain. The number of stressful life events was worked out using another questionnaire that collects information about events such as the death of close friend or relative.

WHAT WERE THE MAIN FINDINGS OF THE STUDY?
Contrary to what had been expected, defects in the biological stress systems did not contribute to people developing chronic pain. However, negative life events such as financial problems, relationship breakdowns and bereavements did trigger the onset of chronic pain. People were also more likely to develop chronic pain if they were older, female, had higher pain scores at the beginning of the study, had higher evening cortisol (a stress hormone), used medicine for their heart, or if they had a lower level of education. People who were overweight, had other diseases or depression or anxiety were also more likely to experience chronic pain. The authors concluded that negative life events could trigger chronic pain independently of the biological stress system, sociodemographics, lifestyle, chronic diseases, depression and anxiety.

ARE THESE FINDINGS NEW?
The current understanding of the causes of chronic pain is very limited. It has previously been found that negative life events can trigger the onset of chronic pain. However, these findings suggesting that biological stress systems are not involved in the onset of chronic pain are new. This is important because it suggests that future research should look at other biological systems such as the brain.

WHAT ARE THE LIMITATIONS OF THE STUDY?
The authors assessed the biological stress systems in just one day. They did not look at whether there were changes over time. In addition, they were not able to study the onset of fibromyalgia, which is a type of chronic pain.

WHAT DO THE AUTHORS PLAN ON DOING WITH THIS INFORMATION?
The authors suggest that future research should focus on the role of the brain in chronic pain, and on negative life events as triggers of impaired functioning in the brain.

WHAT DOES THIS MEAN FOR ME?
Chronic pain can cause sleep disturbance, extreme tiredness and depression, and it can cause people to limit their physical activity. If you have chronic pain, these results may help you to understand better what may have caused it. You should try to resolve negative events that may have triggered your chronic pain. Talking to a personal development trainer or a psychologist might help. You should also take steps to ensure that you maintain a healthy diet and lifestyle, including regular physical exercise. Further research in this area may help to develop treatments for people with chronic pain.

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Date prepared: May 2016

Summary based on research article published on: 22 April 2015

From: Generaal, E. et al. Biological stress systems, adverse life events and the onset of chronic multisite musculoskeletal pain: a 6-year cohort study. Ann Rheum Dis 2016;75:847–54. doi:10.1136/annrheumdis-2014-206741

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FURTHER READING
1 Help manage your rheumatic and musculoskeletal disease. Available at: www.worldarthritisday.org
2 Dejaco C, et al. 2015 Recommendations for the management of polymyalgia rheumatica: a European League Against Rheumatism/American College of Rheumatology collaborative initiative. Ann Rheum Dis 2015;74:1799–1807. Available at: http://www.eular.org/recommendations_management.cfm
3 Carville SF, et al. EULAR evidence based recommendations for the management of fibromyalgia syndrome. Ann Rheum Dis 2007;67:536–41. Available at: http://www.eular.org/recommendations_management.cfm